Preparation of titanium hydroxide



' 45 (from thepoint Reissued Sept. 10,1929.

UNITED; STATES PATENT OFFICE.

JOSEPH momentum), or rARrs, FRANCE, ASSIGNOR, BY mnsnn ASSIGNMENTS, To 1ooIrmnnoI L rremnn'rs CORPORATION, A CORPORATION or DELAWARE.

PREPARATION or rirANIuM nrnaoxrnn;

No Drawing. Original 1T0. 1,504,672, dated August 12, 1924, Serial No.690,658, filed February 4, 1924.

' Application for reissue filed June 12, 192B. Seria1 No. 284,679..

DmsIoN B.

The invention relates to the hydrolytic treatment of solutions oftitanium oxide in sulfurio acid with the object of preparing thehydroxide of titanium. a v 5 Such solutions are obtained by treatingtitaniferou's products or minerals, such as ilnienite, with sulfuricacid.

The chemical composition of these solutions may vary within fairly widelimits. The two most important variables are the concentrations of TiOand H 80 Solutions containing from 100 to 400 grams TiO per liter are ofthe usual strengths to be treated. For a molecule of'TiO the solutionshould contain 12 or even more molecules oi; H SO It has nowbeen foundthat the yield of titanium hydroxide obtained by hydrolyticprecipitation of such solutions (heated to 10 about 100 C. during acertain time) as wellas its properties, such as the rate of decantation,filtrability, state of subdivision of grain, color after calcination,etc., depend not only on the final state of the system subjected to Z5hydrolytie treatment but they depend also upon certain transformationswhich the constituents of the solution undergo before and during theprecipitation of the titanium I dioxide andalso upon the way in whichthis final state of reaction is brought about. In efiect, the solutionof TiO; in H SO brought to a desired concentration either b dilution orbyconoentration, is heatedto'the ing point in orderto produce the'hydrolysis and becomes opaque after a comparatively long time, but ifthe content in H,,S O combined'with T10 neglecting other bases, is

equal to or exceeds 100 grams per litre, a very V npoor yield intitanium hydroxide is obtained.

40 Moreover, the precipitate thusobtained, even if possible,'is onlyfiltered with great difliculty.

fore is tov obtain a satisfactory precipitate of. view .ofyield', Ifiltra ility v and other roperties) in' a shorttiine from solutions 0the type mentioned above even in Y high concentrations. i

The invention cons stsinpre aring P lium oxideor hydrox de by,

boil-, i

. the concentrated solution.

The object of the present inventionptlierel mixing. The mixin 1y quicklyin order t cipitation by diffusion of titanium from one solution intoanother under the action of diiferential concentration and preferablyalso temperature.

Theinvention further consists in preparing titanium-oxide or hydroxideby hydrolytic precipitation by diliusion of titanium from one solutioninto another accelerated by mixing.

1 v The invention also consists in applying the above processes inthepresence of other substances so that intimately mixed precipitates areobtained.

Generally, the methods employed are as follows: a

(1) The solution obtained by reacting on the titanium material withsulphuric acid, heated to a temperature excee'dingfiO? 0., iscoveredwith a layer of cold water or hot water, either pure orcontaining such I substances as may favor the process such, for example,as H 50 H PO,, A1;, (S0,) S0,, or: even a solution of titanium salt of adifferent concentration. The quantity of the 1iq-,, uid added iscalculated so as to produce on diffusion or mixing together the desiredconcentration. The liquid is introduced in such .a' manner that the twoliquids 'may mix together only gradually, and thus within a certaintimethere will be a difit'erence in concentrations in diflerent parts ofthe solution as regardsH SO and TiO (2) In another or modified methodthe solution is concentrated by evaporatin or boiling and may evenbecome thick 1i e a paste. When the necessary quantity of water has beeneliminated according to the object, the solution is mixed with asmaller, equal 'or larger quantity of water than that eliminated. One ofthe liquids must be at that time at a temperature above 60 C.-usuallyThe water may be 'pureorfcontaining some substances, such as titaniumsalt or the like. The proportions of v the two liquids are selected soas to have the desired concentration, both in 'TiO and H,SO in the finalstate after the complete at the titanium hydroxide does noflprecipitateappreciably etore should be efiected fair the homogeneity of thesolution is achieved and heating continued.

In both cases the hydrolytic precipitation is terminated at atemperature not far from .the boiling point of the solution and in atitanium hydroxide is precipitated. in presence of other substancesadapted to serve as constituents of paint pigments, (such as BaSO CaSOSiO and the like) with which it is desired to mix it very intimately.The added substances may be prepared separately or in the same apparatusin which the hydrolysis takes place.

ing temperature, eva oration being Example 1. The solutioncontaining Gr.per litre. TiO ".225 Fe 50 H,SO tota1 44.0

isheated to 9598 and alayer of cold water is placed on the top inquantity correspond ing to about 20 per cent of its volume. This amountof water is suflicient to reduce the total H 80 content to about 367rams per litre. The mixture of the liquid is acilitated by a gentleagitation. The liquid becomes titanium sulfate with a solution of lesserconcentration, and retarding the rate of admixture so that the composite1i uid first becomes gradually turbid and therea r throws down thedesired precipitate.

2. The preparation of titanium dioxide or hydroxide by hydrolyticprecipitation which comprises bringing together a solution of titaniumsulfate with water, and retarding the rate of admixture so that thecomposite liquid first becomes gradually turbid and thereafter throwsdown the desired precipitate. 1

3. The preparation of titanium dioxide or hydroxide by hydrolyticprecipitation, which fate with a layer of solution o'flesserconcentration so that the composite liquid becomes gradually turbid andthereafter throws down the desired precipitate.

4. The'preparation of titanium dioxide or hydroxide by hydrolyticprecipitation, which comprises introducing cold water into a Warmsolution of titanium sulfate in that proportions of about 20% of thevolume of the titanium sulfate solution and in such 'a manner as to forma layer of-water upon the titanium sulfate solution.

JOSEPH BLUMENFELD. T

gradually turbid and then a precipitate falls down. By the end of a fewhours the yield of titanium hydroxide is about 94: per cent.

Example Q. The solution containing:

Gr. per litre. Ti0 Fe 4:2 H SO, 460

is concentrated by evaporation to half its volume. It then has theconsistency of a paste. It is introduced into about twice its own volumeof boiling hot water so that the concentration finally will be 300-310gr. H SO per litre. The mixing is effected in'such a manner as to avoidthe immediate coagulation (precipitation) by delaying the mixing from 3to 5 minutes. It is maintained at boilrevented. In-about hal an hour ayield? of 85-95 percent of titanium hydroxide is obtained. I Now, havingfully described my invention, I claim the following as new and novel: 1.The preparation of titanium dioxide or .hydroxide by hydrol'ytioprecipitation which comprises bringing together a. solution of comprisescovering a solution of titanium sul

